Wave signaling system



Feb. '7, 1928. 1,658,638

L. A. HAZELTINE WAVE SIGNALING SYSTEM Filed July 18, 1925 OUTPUT 100/: AHAZELTWE I limlw ETENTOR ATTORNEYS Patented Feb. 7,1928. I

UNITED STATES PATENT OFFICE.

LOUIS A. nAzELrI'NE, OF HOBOKEN, NEW JERsEY, ASSIGNOR T nezntrmn con. ronnrron, on JERSEY our, NEW JERSEY, A coRroRArIoN or DELAWARE.

'WAYE SIGNALING sYsrEm.

Application filed July 18, 1925. Serial No. 44,509.

The purpose of this invention is to annul the effect of the capacity coupling existing between the grid and the plate circuits of a vacuum tube so as to prevent regeneration and the consequent production of undesired oscillation, particularly when the grid and plate circuits are tuned to the same frequency. This invention difiers from methods in which the capacity coupling bein tween the grid and the plate circuits is neutralized in that the capacity coupling between the grid and the plate circuits is allowed to remain, but its regenerative effeet is prevented' This is accomplished in by arranging in a manner'to be described an opposition coil connected in the grid circuit directly in series with the grid itself and with the tuned input circuit. This results in anti-regeneration with respect to the an output circuit-that is,.the effective resistance of the output circuit is increased. While such increases in' resistance may be disadvantageous at times, it may under certain circumstances be an advantage, or at to any rate no detriment because its eiiect may be counteracted. For example, if the vacuum tube in question is followed by a regenerative vacuum tube, its anti-regeneration may be counteracted by theregeneram tion of the followin tube. Again, in a super-regenerative circuit added resistance, or its equivalent, is generally necessary; and this may advantageously and conveniently be provided by the arrangement of this invention.

Referring to the drawings:

Fig. 1 is acircuit diagram showing a single tube arranged in accordance with this invention.

Fig. 2 shows an amplifying vacuum tube employing this invention and followed by, a regenerative detector. I

Fig. 3 shows this invention applied to a super-regenerative system.

Referring to Fig. 1, the input circuit is led to the primary coil ofa transformer whose secondary circuit (3,, L is tuned. For convenience, a combination of capacity and inductance, at least one of which is variable, may be called, a tuning unit. In series with this secondary circuit is a coil having the number of turns N The plate circuit of the vacuumtube includes a coil having the number of turns N, closely coupled to the coil N, and also coupled to the voltages would exist across N and N coil L which is tuned by condenser 0 and which leads to the output circuit. The capacity whose regenerative coupling efi'ect to be annulled is that indicated by C existing between the grid and the plate. There Wlll also exist natural capacity C between the grid and the filament, which will affect the opposition relation, although complete opposition could equally well be effected in accordance with this invention in case this capacity C were negligible.

The theory of operation in Fig. 1 is as follows: Assume that the turns N and N, are coupled together with a coeificient of coupling substantially equal to unity and are arranged so that the grid and plate are of the same polarity. Then, if an oscillation should be started in the output circuit, 8 1n proportion to theirrespective numbers of turns. If there is to be zero voltage across C and L as is desired, the same current must flow through C as through (1,. The current throu h C will be proportional to C and to The current through C will be proportional to (1 and to the dif ference between N and N We must then have the relation The result of the above relation then is that an oscillation in the tuned output circuit is not communicated to the tuning unit in the input circuit; so no interaction between these circuits can occur. However, an oscillation present in the output circuit does afi'ect the potential of the rid (by the voltage induced in the coil N and this potentialis of. such a sense as to have an anti-gegenerative efiect with respect to the output circuit, adding efiectively to its resistance, but

not aifecting the resistance ofthe input circuit. Thiseifective increase in resistance inay readily be counteracted, as described be- Fig. 2 shows the arrangement of Fig. 1 applied to radio reception in which the vacuum tube A is a combined radio-frequency and audio-frequency am lifier, in accordance with the reflex principle, and the'vacuum tube D is a regenerative detector. The no;

coils N N and L correspond with those of Fig. 1 and operate in the same Way to prevent interaction'between the tuned circuits C L and C L However, there is added to the detector tube the plate coil L which is adjustably coupled toN N and L It functions to effectively reduce the resistance of the tuned circuit 0,, L and thereby overcomes the anti-regenerative effect due to N,;.

In the adjustment of the set it may not be convenient to have the coil N coupled with N at substantially unity coefiicient of coupling. In practice, the number of turns N or the coupling of this coil with N is adjusted by trial in such a way that an oscillation present in the detector tube circuit is not transmitted to the tuning unit (1,, L, in the input circuit. This is most simply ascertained by adjusting N in such a way that the variation of C does not appreciably affect the oscillation in the detector tube circuit.

The resistances, fixed condensers, audiofrequency transformer, telephone and batteries in Fig. 2 have their usual functions.

Fig. 3 shows a two-tube super-regenerative circuit in which the tube A generates the variation frequency and the tube D is the detector. The variation frequency is the natural frequency of the unit C, L, which is coupled to the coil L" in the grid circuit of A. The transfer of oscillations from the tuned circuit of the detector tube to the tuned antenna circuit C,, L is prevented by the use of the coils N and N as in the preceding figures. This has, as in Fig. 2, the important advantage of preventing radiation from the antenna, even though an oscillating detector tube is employed. In Fig. 3 the two coils N and L of Fig. 2 have been combined into a single coil N,,; and, in place of connecting the tuning condenser across the secondary coil L it is now connected across N,,, as represented by the variable capacity C The plate circuit of A thus acts as the variable load on the plate circuit of D. This is a particularly suitable arrangement as the conductances of the two plate circuits will be of the same order of magnitude if like tubes are employed; and this gives a proper value of conductance for good superregenerative action. The adjustment of the turns N and their coupling to N is effected in the same way as in Fig. 2. a

I claim:

, 1. In a vacuum tube amplifier having a grid, a plate and a filament, an input circuit including a tunin unit tunable over a substantial range in requency, said tuning unit comprising inductance and a variable capacity in parallel connected to the grid and the filament, an output circuit connected to the plate and the filament, and inherent capacity coupling between the grid and the plate and the circuit leads connected thereto, the

method of annulling the regenerative effect of said capacity coupling which comprises introducing directly in series with the grid and external to said tuning unit a voltage derived from the output circuit, whereby any oscillation occurring in the output circuit is prevented from being communicated through said inherent capacity to said tuning unit in the input circuit.

2. In a vacuum tube amplifier having a grid, a plate'and a filament, an input circuit including a tuning unit tunable over a substantial range in frequency, said tuning unit comprising inductance and a variable capacity in parallel connected to the grid and the filament, an output circuit connected to the plate and the filament, and inherent capacity coupling between the grid and the plate and the circuit leads connected thereto, the method of annulling the regenerative effect of said capacity coupling which comprises introducing directly in series with the grid and external to said tuning unit a voltage derived from the output circuit and proport onal to and in phase with the voltage of tie output circuit, whereby any oscillation occurring in the output circuit is prc vented from being communicated through said inherent capacity to said tuning unit in the input circuit.

3. In a vacuum tube amplifier having a tuned input circuit and a tuned output circuit, the latter including a coil in the plate circuit, a coil connected directly in series with the grid, external to said tuned circuit, coupled to said coil in the plate circuit with a coeflicient of coupling substantially equal to unity and with such polarity that the grid and plate are of like polarity, and having a ratio of turns to said coil in the plate circuit equal to the ratio of the grid-plate capacity to the sum of the grid-plate capacity and the grid-filament capacity.

4. In a vacuum tube amplifier having a grid, a plate and a filament, an input circuit including a tuning unit tunable over a substantial range in frequency, said tuning unit comprising inductance and a variable capacity in parallel connected to the grid and the filament, an output circuit connected to the plate and the filament, inherent coupling capacity between the grid and the plate and the circuit leads respectively connected thereto, whereby atendency towards oscillation is produced, and means associated with the input circuit and with the output circuit for intro'ducin directly in series with the grid and external to said tuning unit a voltage derived from said output circuit, whereby any oscillation occurring in the output circuit is substantially prevented from being communicated thru said inherent capacity to the tuning unit in the input circuit.

5. In a vacuum tube amplifier having a grid, a plate and a filament, an input circuit including a tunin unit tunable over a substantial range in requency, said tuning unit comprising inductance and a variable capacity 1n parallel connected to the grid and the filament, an output circuit connected to the plate and the filament, inherent conpling capacity between the grid and the plate and the circuit leadsrespectively connected thereto, where'bya tendency towards oscillation is produced, and means associated with. the input circuit and with the output circuit for introducing directly in serieswith the grid and external to said tuning unit a voltage derived fromthe output circuit and proportional to and in phase with the voltage of the'output circuit, whereby any oscillation occurring in the output circuit is substantially prevented from being communicated thru said inherent capacity to the tuning unit in the input circuit.

6. In .a vacuum tube amplifier having a grid, a plate and a filament, an input circuit including a tuning unit tunable over a substantial range in frequency, said tuning unit comprising an inductance and a variable condenser in parallel, and being connected to the grid and t0 the filament, an output circuit connected to the plate and to the fila-' and filament and electromagnetically coupled to said first-named coil for introducing directly in series with the grid and external to said tuning unit a voltage derived from said output circuit, whereby oscillations occurring in the output circuit are substantial- 1y prevented from being communicated through said inherent capacity to said tuning unit in the input circuit,

In testimony whereof I afix my signature.

LOUIS A. f LTINE. 

